Pyogenic cocci the gram s positive cocci 1 staphylococci 2 streptococcus
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Pyogenic Cocci : The Gram’s positive Cocci : 1- Staphylococci : 2- Streptococcus : PowerPoint PPT Presentation


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n. Pyogenic Cocci : The Gram’s positive Cocci : 1- Staphylococci : 2- Streptococcus : Staphylococci : is a Gram positive Cocci , one micrometer in diameter, arranged in clusters, non spore formers, and non-motile. Staphylococcus aureus species are capsulated. n.

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Pyogenic Cocci : The Gram’s positive Cocci : 1- Staphylococci : 2- Streptococcus :

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Pyogenic cocci the gram s positive cocci 1 staphylococci 2 streptococcus

n

Pyogenic Cocci: The Gram’s positive Cocci:

1-Staphylococci :

2-Streptococcus :

Staphylococci :

is a Gram positive Cocci, one micrometer in diameter, arranged in clusters, non spore formers, and non-motile.

Staphylococcus aureus

species are capsulated.


Pyogenic cocci the gram s positive cocci 1 staphylococci 2 streptococcus

n

Staphylococcus species are facultative anaerobic bacteria.

All species grow best on nutrient agar and blood agar.

Mannitol salt agar is a selective media for Staphylococcus species.

It can grow at a temperature range of 15-45 C, and NaCl concentration as high as 15%.


Pyogenic cocci the gram s positive cocci 1 staphylococci 2 streptococcus

n

Clinical significance of Staphylococcus aureus:

1-Localized skin infections.

2-Acute endocarditis.

3-Pneumonia.

4-Septicemia.

Staphylococcusimpetigo

5-Food poisoning:(foodborne intoxication).


Pyogenic cocci the gram s positive cocci 1 staphylococci 2 streptococcus

n

Streptococcus :

Gram positive cocci,occur in pairs and in short chains.

None-motile, none- spore formers, some strains are capsulated.

Strict anaerobes and facultative anaerobes.

Gram positive

Streptococci:

in chains.


Classification of streptococcus species

Classification of Streptococcus species:

Streptococcus species are classified according to hemolytic activity.


Pyogenic cocci the gram s positive cocci 1 staphylococci 2 streptococcus

n

Beta-Hemolytic: Alpha Hemolytic

Streptococcus pyogenesStreptococcus pneumoniae


Pyogenic cocci the gram s positive cocci 1 staphylococci 2 streptococcus

n

Clinical significance of Streptococcus pyogenes:

1-Acute pharyngitis and tonsilitis.

2-Impetigo and deep skin

infection.

3- Acute Rheumatic fever.

Due to the bacteria M protein.

Streptococcus tonsilitis

4-Acute nephritis.

Due to antibodies interaction with glomerulus.


Pyogenic cocci the gram s positive cocci 1 staphylococci 2 streptococcus

n

The Gram negative Diplococci:

Neisseria meningitidis

Neisseria gonorrhoeae

Gram negative cocci , Kidney-shaped, occur in pairs, in clinical specimens: present inside the polymorphonuclear cells.


Pyogenic cocci the gram s positive cocci 1 staphylococci 2 streptococcus

n

They grow best on Thayer-Martin Medium; Chocolate agar supplemented by vancomycin and nystatin.

Both factor X and V (hemoglobin, NAD) are required for Neisseria species cultivation.

A 5-10 % CO2 is required for primary cultivation.

Neisseria growth

On Chocolate agar.


Pyogenic cocci the gram s positive cocci 1 staphylococci 2 streptococcus

n

Clinical significance:

Neisseria meningitidis

Meningococcal disease

1-Meningitis

2-Septicemia

Neisseria gonorrhoeae

1-Urinary tract infection: (Most common):

A- Gonococcal Urethritis.

B- Pelvic inflammatory disease


Pyogenic cocci the gram s positive cocci 1 staphylococci 2 streptococcus

Gram positive Bacilli

n

Branching

Non-Branching

Actinomyces

Spore formers

Non-spore formers

N

Aerobic

Anaerobic

Acid-fast

Non-acid fast

Bacillus anthracis

Bacillus cereus

Clostridium perfringens

Clostridium tetani

Mycobacterium

Corynebacterium

Listeria

Lactobacillus


The gram s positive spore former aerobic bacilli

The Gram’s positive spore former aerobic bacilli:

The genus Bacillus:

Gram-positive spore-forming, non-motile, bacilli arranged in chains.

Bacillus anthracis species are capsulated in tissue and spore-former

in the culture.

Gram’s stain smear Malachite green spore stain.


Pyogenic cocci the gram s positive cocci 1 staphylococci 2 streptococcus

n

Bacillus anthracis grows on nutrient agar or blood agar in presence of oxygen (obligate aerobic bacteria).

On the blood agar, Bacillus anthraciscolonies are non-hemolytic,with irregular border.

Growth of Bacillus cereus

andBacillus anthracis.


Pyogenic cocci the gram s positive cocci 1 staphylococci 2 streptococcus

n

Clinical significance:

Bacillus anthracis :

1-Cutaneous anthrax:

Spore germination in skin,

a papule development,

converted into malignant

pustule.

2-Pulmonary anthrax :

(Woolsorter’s disease):

-hemorrhagic lymphadenitis.

Bacillus cereus:

Enterotoxins cause food poisoning.


The gram positive spore forming anaerobic bacilli

The Gram positive spore-forming anaerobic bacilli:

The genus Clostridium:

Gram-positive spore-forming, anaerobic large bacilli.

Clostridium tetani species forms terminal spores, while sub-terminal or central oval spores are produced by Clostridium perfringens.

Microscopic Drum-stick

Appearance of

Clostridium tetani


Pyogenic cocci the gram s positive cocci 1 staphylococci 2 streptococcus

n

All Clostridium species are obligatory anaerobic.

On blood agar, Clostridium perfringensspecies produce zone of complete hemolysissurrounded by wider zone of incomplete hemolysis.

Clostridium tetani colonies show beta hemolytic activity.


Clinical significance

Clinical significance:

Clostridium perfringens:

1-Myonecrosis (gas gangrene):

Caused by alpha toxin which damages host and blood cells.

2-Food poisoning: caused by Enterotoxin.


Pyogenic cocci the gram s positive cocci 1 staphylococci 2 streptococcus

N

Clostridium botulinum :

-Botulism:

Food poisoning, lead to progressive striated muscle paralysis .

Clostridium tetani:

-Tetanus :General muscle paralysis.

Clostridium difficile:

-Diarrhea, and pseudomembranous colitis due to long-term

antibiotic therapy.


The non spore former acid fast bacilli

The Non-spore former acid-fast Bacilli:

The genus Mycobacterium:

The Mycobacteriaare acid-fast, non-motile, non-spore forming rods.

The microbe can not be stained well by Gram’s stain due to the presence of waxy capsule.


Pyogenic cocci the gram s positive cocci 1 staphylococci 2 streptococcus

n

Mycobacterium isbest demonstrated by Ziehl -Neelsenstaining technique; the microbes appear as thin pink rods arranged singly or in groups.

Once stained, they resist decolorizationwith 2% H2SO4and

95%alcohol (Acid-fast, Alcohol fast).


Pyogenic cocci the gram s positive cocci 1 staphylococci 2 streptococcus

n

Mycobacteriumis strict aerobic, grows very slowly (2-4 weeks) on Lowenstein-Jensen medium; produce dry creamy colored colonies.

Culture characteristics of Tubercle bacillion Lowenstein Jensen medium .


The non spore non acid fast bacilli the genus corynebacterium

The Non-spore Non-acid fast bacilli: The genus Corynebacterium:

Gram positive pleomorphic long rods with swollen one end (club-shaped).

They lie in small groups joined at angles to each other giving characteristic Chinese-letter arrangement

Corynebacterium bacilli arranged

as Chinese-letter.

Note the metachromatic

Granules.


Pyogenic cocci the gram s positive cocci 1 staphylococci 2 streptococcus

n

Aerobe or facultative anaerobe; grows rapidly on Löffler's medium at 37 C giving opaque white colonies within 4-12 hours.

On blood tellurite;

the organism reduces

telluriteand produce

grey-black colonies


Pyogenic cocci the gram s positive cocci 1 staphylococci 2 streptococcus

a

Clinical significance of Corynebacterium:

1-Upper respiratory tract: Diphtheria.

Pseudo-membrane appearance. Marked lymph node enlargement. 2-Skin infection.

Diphtheria skin lesion.


Pyogenic cocci the gram s positive cocci 1 staphylococci 2 streptococcus

Gram’s negative Bacilli

n

Enterobacteriaceae

Vibrio’s

Curved-S,

U Shaped bacilli

Coccobacilli

Spirochetes

n

Lactose Fermenter

Non-Lactose

fermenter

Vibrio cholera

Treponema

E. coli

Klebsiella

Salmonella

Shigella

Campylobacter

Helicobacter

Brucella


General properties of enterobacteriaceae

General properties of Enterobacteriaceae:

1- Short rods, and non-spore formers.

2- All are motile (by peritichousflagellae) except

Klebsiellaand Shigella

3- Aerobes or facultative anaerobes.

4- Oxidase negative and catalase positive.

5- All ferment glucose with acid or acid and gas production

and reduce nitrate to nitrite.


Pyogenic cocci the gram s positive cocci 1 staphylococci 2 streptococcus

n

Based on lactose fermentation, Enterobacteriaceae species are divided into:

1-Lactose fermenters as: Escherichia coli, Klebsiella

2-Non-lactose fermenters as: Salmonella, Shigella.


Clinical significance of some enterobacteriaceae species

Clinical significance of some Enterobacteriaceae species:

1- E.coli:

Urinary tract infection.

Gastroenteritis.

2-Klebsiella:

Lower respiratory tract infection.

Urinary tract infection.

3-Salmonella:

Typhoid fever, and food poisoning.

4-Shigella:

Dysentery.


The vibrios

The Vibrios:

Vibrios are gram-negative aerobic comma shaped curved bacilli, motile with a single polar flagellum.

Vibrio choleraeserogroups O1 and O139 are responsible of

epidemic cholera.

They grow on different media at high pH (8.5-9.5) as alkaline peptone water and TCBS.


Curved s u shaped bacilli

Curved S, U-shaped bacilli:

The Genus Helicobacter andCampylobacter :

-Gram’s negative pleomorphic S or U-shaped Bacilli.

-Fastidious microbe grow best on Enriched media

supplemented by Bovine serum albumin and antibiotics

-Microaerophilicbacterium(5% O2, 10% CO2)

Clinical significance:

1-Helicobacter:

peptic ulcer disease.

2-Campylobacter:

Gastroenteritis.


Coccobacilli

Coccobacilli:

The Genus Brucella:

Gram-negative non-motile, non-capsulated short coccobacilli.

Aerobic bacteria; grow best on liver extract agar at 5-10%

CO2.


Pyogenic cocci the gram s positive cocci 1 staphylococci 2 streptococcus

n

Clinical significance:

Brucella melitensis: Malta fever.

It is mainly a pathogen of goats and sheep.

It the strain found in the Mediterranean area and Arabian

Gulf.

Brucella abortus:Malta fever.

infects cattle mainly but can infect other animals.


Spirochetes

Spirochetes:

Treponema pallidum:

-Ithas a characteristic helical shape, tightly coiled bacilli like a

telephone cord.

-All are Gram’snegativespiral bacilli with endoflagella

-Because it can not be stained by Gram’s stain;

wet-mount Preparation should be examined by Darkfield-

microscopy.

Clinical significance:

-Primary, secondary, and

late stage Syphilis.


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